The subject of the present invention is a lock device for a loading equipment consisting of a hook-device type arm construction which comprises a rear frame mounted pivotably by means of a transversal, horizontal shaft or articulated joints placed at the rear end of the frame beams of a truck. A middle frame of the loading equipment is pivotably mounted at one of its ends to the rear frame by a transversal, horizontal shaft or articulated joints. At one end of the middle frame an angle piece is mounted as pivotable by means of a transversal, horizontal shaft or articulated joints around the rear end of its horizontal part or parts. The vertical part of the angle piece is at its upper end provided with a grasping means, such as, e.g., a hook, for the purpose of engaging a corresponding grasping component at the front wall of the exchange platform or any other load space. A main cylinder or two parallel main cylinders operating the loading equipment are arranged so that one of their ends is fastened to the frame of the truck and the opposite end to the middle frame of the loading equipment. For the purpose of pivoting the angle piece independently in relation to the middle frame, a cylinder-piston device is arranged between the angle piece and the middle frame, and the rear frame of the loading equipment and the base construction of the exchange platform or any other load space are provided with jointly operative locking means for the purpose of locking the exchange platform or any other load space onto the loading equipment as the exchange platform or any other load space has been pulled into its front position.
When dumping is performed by means of a hook-device type loading equipment, the dumping frequently takes place so that the arm construction of the loading equipment is locked to the base of the exchange platform. This locking has not been secured in any way, and, under these circumstances, if the exchange platform can glide downwards in the dumped position, the locking is opened and the arm construction of the loading equipment can be released downwards at the articulated joint between the rear frame and the middle frame.
An object of the present invention is to eliminate the above mentioned drawback and others. The lock device in accordance with the invention is characterized in that the rear frame of the loading equipment is provided with safety catches placed at both sides of the rear frame so that, when the exchange platform or any other load space is being dumped, the safety catches pivot into the locking position, in which they prevent shifting of the exchange platform or any other load space backwards in relation to the loading equipment. However, the safety catches are opened when the rear frame is turned to the horizontal position, and, moreover, locking means are preferably provided between the truck frame and the rear frame of the loading equipment. The locking means consist of transverse locking pins fitted to the truck frame and of locking levers fitted to the rear frame of the loading equipment and jointly operative with the locking pins. The levers are forced by the exchange platform forced in the transport position forced to the open position, whereas the rear frame is secured to the truck frame when the exchange platform or any other load space rises off the rear frame while the exchange platform or any other load space is being loaded onto the truck chassis or removed from same.